U.S. patent application number 10/239491 was filed with the patent office on 2003-06-05 for multiple-nip calender and calendering arrangement.
Invention is credited to Koivukunnas, Pekka, Linnonmaa, Pekka, Luomi, Seppo, Tani, Mikko.
Application Number | 20030101880 10/239491 |
Document ID | / |
Family ID | 8558004 |
Filed Date | 2003-06-05 |
United States Patent
Application |
20030101880 |
Kind Code |
A1 |
Koivukunnas, Pekka ; et
al. |
June 5, 2003 |
Multiple-nip calender and calendering arrangement
Abstract
The present invention relates to a supercalender for calendering
a paper web and a calendering arrangement for producing mat-quality
paper web. The multiple-nip calender of the invention is
characterized in that at least one of the calendering nips of the
multiple-nip calender is an extended nip (N.sub.9) formed between a
polymer roll (18) and either a shoe roll (30) or a calendering
belt.
Inventors: |
Koivukunnas, Pekka; (US)
; Luomi, Seppo; (J?auml;rvenp?auml;?auml;, FI) ;
Linnonmaa, Pekka; (J?auml;rvenp?auml;?auml;, FI) ;
Tani, Mikko; (Tuusula, FI) |
Correspondence
Address: |
LATHROP & CLARK LLP
740 REGENT STREET SUITE 400
P.O. BOX 1507
MADISON
WI
537011507
|
Family ID: |
8558004 |
Appl. No.: |
10/239491 |
Filed: |
December 27, 2002 |
PCT Filed: |
March 21, 2001 |
PCT NO: |
PCT/FI01/00284 |
Current U.S.
Class: |
100/161 |
Current CPC
Class: |
D21G 1/006 20130101 |
Class at
Publication: |
100/161 |
International
Class: |
B30B 003/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 22, 2000 |
FI |
20000671 |
Claims
1. A multiple-nip calender, such as supercalender, for producing
mat-quality paper web (W) said calender comprising a roll system
composed of a plurality of rolls (11-18, 20, 25, 30, 35; 111-116,
121, 125, 131, 135) arranged to be in nip contact with each other
or a corresponding roll stack (10A, 10B, 10C; 110A, 110B, 110C), in
which a paper web (W) to calender the same is arranged to pass
through the nips (N.sub.1-N.sub.9; N.sub.1-N.sub.7), at least one
of which is an extended nip, characterized in that at least the
first and/or the last calendering nip
(N.sub.1,N.sub.9;N.sub.1,N.sub.7) of the multiple-nip calender is
an extended nip.
2. A multiple-nip calender according to claim 1, characterized in
that the extended nip (N.sub.1, N.sub.9; N.sub.1, N.sub.7) is
formed between two rolls, one of said rolls being an extended nip
roll (20, 25, 30, 35, 121, 125, 131, 135), such as, a shoe roll,
comprising a flexible roll shell (22, 32) arranged to rotate around
a roll support (21, 31), being with the aid of a formed compression
shoe (23, 33) arranged to be pressed against the second roll (11,
18, 111, 116) of the nip, whereby one-sided mat-quality paper web
is produced in each extended nip..
3. A multiple-nip calender according to claim 2, characterized in
that the extended nip (N.sub.1, N.sub.7) is formed between a
polymer roll or a thermoroll (11, 18, 111, 116) and a shoe roll
(20, 25, 30, 35, 121, 125, 131, 135) of the roll stack (10A, 10B,
10C, 110A, 110B, 110C).
4. A multiple-nip calender to claim 3, characterized in that the
calendering nip (N) is formed against the upper polymer roll or the
thermoroll (11, 111).
5. A multiple-nip calender to claim 3, characterized in that the
calendering nip (N) is formed against the bottom polymer roll or
the thermoroll (18, 116).
6. A multiple-nip calender to claim 3, characterized in that the
calendering nip (N) is formed against the upper polymer roll or the
thermoroll (11, 111) and the bottom polymer roll or the thermoroll
(18, 116).
7. A multiple-nip calender according to any one of the preceding
claims 1 to 6, characterized in that the multiple-nip calender is
the multiple-nip calender known from the trademark
Optiload.TM..
8. A multiple-nip calender according to any one of the preceding
claims 1 to 6, characterized in that the shoe roll (30) is the
extended nip roll known by the trademark SymBelt.TM..
Description
[0001] The present invention relates to a multiple-nip calender,
such as supercalender, for producing mat-quality paper web said
calender comprising a roll system composed of a plurality of rolls
arranged to be in nip contact with each other or a corresponding
roll stack, in which a paper web to calender the same is arranged
to pass through the nips at least one of which is an extended
nip
[0002] The roll system of a conventional supercalender comprises a
number of rolls, usually 8 to 14 rolls, arranged into a
superimposed roll stack. The superimposed rolls are in nip contact
with each other and the paper web to be calendered is arranged to
run through the nips between the rolls. Also such supercalenders
are known in the art in which the rolls of the roll system are so
arranged that the nip level mainly common to the roll nips is
arranged to be essentially horizontal instead of using a vertical
roll stack. As regards the calendering result, it is not, however,
of great importance whether a vertical or horizontal roll system is
used. A highly conventional supercalender design is disclosed in
e.g. FI patent specification No. 81 633.
[0003] When wishing to raise the level of calendering with
currently known designs, the sole possibility is, in fact, to
increase the number of calendering nips in the super-calenders.
This leads to a more complicated calender structure and to a more
difficult control and tail threading of the paper web. Especially,
when on-line machines are in question, the conflicts caused by
great running speed and full-speed tail threading. Endeavours are
made to solve the problems by e.g. different belt and shoe
calenders, with which the calendering nip is extended and,
therethrough, the activity of the nip is intensified. As to the
state of art related to belt calenders, reference is made, for
instance, to Finnish patent specifications Nos. 95 061, 102 304 and
102 305. As regards the state of art related to shoe calenders,
reference is made further to German application specification No.
43 44 165 and U.S. Pat. specification No. 5,163,364.
[0004] Using belt calenders and shoe calenders, a gloss
corresponding to a supercalendered quality or fairly close to the
gloss achieved by supercalendering is achieved, though achieving an
equivalent smoothness is difficult. In order to avoid one-sidedness
problems of the calendered paper, it is in general indispensable to
use at least two extended nips provided with a belt or a shoe roll.
In a belt and shoe calender nip, the maximum pressure will be lower
thanks to the wider nip than in conventional nips formed between
two rolls, because of which the belt and shoe calenders are best
appropriate for paper grades in which the maintaining of bulk is of
a great importance. They are thought to be particularly well
appropriate for use in calendering cardboard.
[0005] According to the prior art, when calendering a paper web to
achieve a mat-quality paper web, the calendering nip is formed
between a polymer roll and a specially coated, heatable thermoroll
or between two polymer rolls. The problem is now especially the
short nip area in the running direction of the web involving
detrimental resulting effects caused thereby in producing
mat-quality paper web.
[0006] A first objective of the present invention is to provide a
novel solution in a multiple-nip calender, by which solution are
provided as a combination those advantages which are related to
current multiple-nip calenders and to e.g. belt and shoe calenders
provided with an extended nip.
[0007] A second objective of the present invention is to provide a
novel calendering arrangement for forming a calendering nip in
order to make feasible production of mat-quality, that is,
non-gloss and smooth paper web easier than before, especially a
more easily controllable calendering when producing mat-quality
paper web.
[0008] To achieve the objects of the invention, the multiple-nip
calender of the invention mentioned at the beginning is mainly
characterized in that at least the first and/or the last
calendering nip of the multiple-nip calender is an extended
nip.
[0009] With the present invention, a plurality of advantages are
gained known in prior art technology, and for instance the
following of said advantages may be introduced in the present
context. In the invention the properties of an extended nip and a
conventional supercalender are combined, whereby, especially when
using an extended and low-pressure nip as the first nip of the
calender, paper can be heated, platisized and worked appropriately
with this kind of extended and low-pressure nip prior to the actual
nips of the supercalender. In this manner, the bulk of the paper
can be saved without compromising over other quality-related
characteristics. With the aid of the invention, the quality
properties of superior paper are achieved in one and same paper
density. With an extended nip connected to the supercalender, the
paper gloss is increased by reducing the microroughness. The gloss
and smoothness of the paper are in general superior to conventional
designs and the uniformity of pressed gloss is better than earlier.
The calendering process is in general a highly "violent" measure
considering the paper, but especially when a nip extended in the
manner disclosed in the invention is used as a first nip of the
supercalender, it will not cause stress to the paper to the extent
the conventional nips do, whereby the structure of the paper will
not suffer in the calendering. The strength properties of paper
remain good. With the design of the invention, more
surface-directional forces are achieved and on the strength of said
surface-directional forces and plastisizing of the web, the
smoothness of the paper to be calendered also exceeds the
conventional level.
[0010] Of the advantages of the invention related to producing a
mat-quality paper web, one may mention that an extended nip and, as
a result of calendering, an excellent and non-gloss microsmoothness
of the surface are achieved. However, the quality of the
calendering result is limited in that if so-called Bendsen
smoothness is desired, other calendering designs have to be
used.
[0011] The other advantages and characteristic features of the
invention become obvious in the following detailed description of
the invention.
[0012] The invention is described below in exemplary fashion,
reference being made to the figures of the accompanying
drawing.
[0013] FIGS. 1A, 1B and 1C present various embodiments of the
invention, in which in a multiple-nip calender such as
supercalender, at least one extended nip is arranged with the aid
of an extended nip roll.
[0014] FIGS. 2A, 2B and 2C present various embodiments of the
invention, in which in a multiple-nip calender such as
supercalender, at least one extended nip is arranged with the aid
of a belt device including a calendering belt.
[0015] FIG. 3 presents an advantageous embodiment for producing
mat-quality paper web.
[0016] FIG. 4 presents a second advantageous embodiment for
producing mat-quality paper web.
[0017] FIG. 1A is a completely schematical and principle
presentation of a supercalender comprising a roll stack 10A
composed of rolls arranged to be superimposed, in which the rolls
of the roll stack form calendering nips N.sub.1-N.sub.9
therebetween, wherethrough a paper web W to be calendered is
arranged to pass. In the presentation of FIG. 1A, a first nip
N.sub.1 of the supercalender is an extended nip formed between an
extended nip roll 20 and a first intermediate roll 11 of the
calender. In the present embodiment, the extended nip roll is
advantagouesly a SymBelt.TM. roll. Said extended nip roll comprises
a roll support 21, whereupon a flexible roll shell 22 is arranged
to rotate, a so-called hose shell. Towards the nip N.sub.1, the
hose shell 22 is pressed with the aid of a formed compression shoe
23. A paper web W to be calendered is conducted to the first nip
N.sub.1 with the aid of a guide roll 41 and it is taken off from
the nip by means of a pull-out roll 42 so that the paper web is
released from the surface of the first intermediate roll 11.
Respectively, after each nip the paper web is released from the
surface of the calender roll with a pull-out roll 42 through 49,
and respectively, it is conducted from the pull-out roll to a
subsequent nip. From the last nip N.sub.9, being in FIG. 1A formed
between the last intermediate roll 18 and the lower roll 35 of the
supercalender, the paper web W is conducted for instance to a
reeler.
[0018] FIG. 1B presents a principle image of a second embodiment of
the invention, in which the roll stack of the supercalender is
indicated by reference 10B. In the parts in which FIG. 1B is
equivalent to FIG. 1A, the same references are used. In an
embodiment of FIG. 1B, a first nip N.sub.1 of the supercalender is
a conventional roll nip formed between an upper roll 25 and a first
intermediate roll 11 of the supercalender. In said embodiment, the
last nip N.sub.9 of the calender is an extended nip formed between
the last intermediate roll 18 and the extended nip roll 30 used as
the bottom roll. The extended nip roll is advantagoeusly a
SymBelt.TM. roll. Thus, the extended nip roll 30 is equivalent in
structure to the extended nip roll 20 presented in FIG. 2A in that
the roll 30 comprises a roll support 31, on which a flexible roll
shell is arranged to be rotating, a so-called "hose shell". The
hose shell 32 is compressed against the last intermediate roll 18
with the aid of a formed press shoe 33 for forming the extended nip
N.sub.9. The web is taken out from said last nip N.sub.9 with the
aid of a guide roll 50.
[0019] FIG. 1C presents one more principle embodiment of the design
of the invention. In FIG. 1C, the roll stack of the calender is
denoted with reference 10C and the same reference numerals are used
in FIG. 1C as in the parts in common in FIGS. 1A and 1C. The
principle presentation of FIG. 1C is in a way a combination of the
designs shown in FIGS. 1A and 1B in that in the present example
both the first nip N.sub.1 and the last nip N.sub.9 of the
supercalender are extended nips. Said extended nips N.sub.1,
N.sub.9 are formed in a manner similar to those described in
association with FIGS. 1A and 1B, in this aspect, reference is made
to the description of FIGS. 1A and 1B.
[0020] FIG. 2A presents one more alternative embodiment of the
design of the invention. In said presentation of FIG. 2A, being a
completely principle image of the supercalender, the roll stack of
the calender is marked with reference 110A. The presentation of
FIG. 2A is to a large extent equivalent to the embodiment shown in
FIG. 1A in that also in the presentation of FIG. 2A the first nip
N.sub.1 of the calender is formed into an extended nip. Said
extended nip N.sub.1 is provided with the aid of a belt device 122,
123, said belt device comprising a calender roll 121, around which
a calendering belt 123 is conveyed, said belt being formed into an
endless link and supported with the aid of guide rolls 122. Thus,
the calendering belt 123 passes from the extended nip N.sub.1
between the calender roll 121 and the first intermediate roll 111.
The intermediate rolls of the calender are therefore indicated by
reference numerals 111 through 116. As in the presentation of FIG.
2A, the paper web W is conducted to the first calendering
nip.sub.1, from which it is taken out with the aid of a pull-out
roll 141 and conducted to a subsequent calendering nip N.sub.2,
from which it is taken out with the aid of a subsequent pull-out
roll, etc. So, pull-out rolls are marked with reference numerals
141 through 146. Finally, the paper web is conducted to the last
calendering nip N.sub.7 formed between the last intermediate roll
116 and the lower roll 135 of the calender. From said last
calendering nip, the paper web is guided e.g. to a reeler.
[0021] The embodiment of FIG. 2B is to a large extent equivalent to
that shown in FIG. 1B in that the first nip N.sub.1 of the calender
also in FIG. 2B is a conventional roll nip formed between an upper
roll 125 of the calender and a first intermediate roll 111. In the
present embodiment, the last nip N.sub.7 of the calender is,
instead, an extended nip formed between a last intermediate roll
116 of the calender and the belt device 130. The belt device 130 in
turn is equivalent to the belt device 122, 123 as in FIG. 2A in
that the belt device 130 comprises a calender roll that is
equivalent to calender roll 131 of FIG. 2C and wherearound a
calendering belt 133 formed into an endless link is conveyed, said
calendering belt being supported with the aid of guide rolls 132.
In the presentation of FIG. 2B, the paper web passes in the manner
equivalent to FIG. 2A between the nips N.sub.1 through N.sub.7 of
the calender so that from the nip N.sub.6 before the last nip of
the calender the paper web is conducted with the aid of pull-out
rolls 147 and 148 into an extended nip N.sub.7 between the belt
device 130 and the last intermediate roll 116. The roll stack of
the calender is denoted with reference 110B. In other respects, the
calender of said embodiment is equivalent to that shown in FIG. 2A
and therefore, the equivalent parts are referred to by same
reference numerals. In this respect, reference is thus made to the
description of FIG. 2A.
[0022] FIG. 2C presents further an additional embodiment of the
design of the invention and the calender presented in FIG. 2C is in
a way a combination of the calenders of FIGS. 2A and 2B in that
both the first nip N.sub.1 and the last nip.sub.7 of the calender
of FIG. 2C are extended nips. Said extended nips N.sub.1 and
N.sub.7 are formed with the aid of belt devices 122, 123 and 130 in
the manner shown in FIGS. 2A and 2B. The roll stack of the calender
is indicated by references 110C in FIG. 2C. In other respects, the
embodiment of FIG. 2C is equivalent to that shown in FIGS. 2A and
2B and therefore, reference in the present context is made to the
description of FIGS. 2A and 2B.
[0023] FIG. 3 presents a one-nip calender of an advantageous
embodiment of the invention for coating a mat-quality paper web. A
paper web W to be calendered is conducted in the direction shown by
an arrow into a calendering nip N, which is an extended nip, formed
between a rotating polymer roll 18 and a thin-shelled, flexible
shoe roll 30 rotating about a fixed axial body. The shoe roll 30 is
preferably an extended nip roll marketed by the applicant under his
trademark SymBelt.TM.. The flexible shell of the shoe roll 30 is
loaded by a radially inside formed loading shoe 33 disposed onto
the axial body to be radially movable, with the aid of which the
flexible shell 32 of the shoe roll 30 is pressed against the shoe
roll 18. Thus, the polymer roll 18 acts as a stop roll to the shoe
roll 30 for forming a calendering nip N.
[0024] FIG. 4 presents a multiple-nip calender of a second
advantageous embodiment of the invention for coating mat-quality
paper web. The paper web W to be calendered enters in the direction
of an arrow into the calendering nip N, which is an extended nip
and which in the embodiment of the figure is formed against the
upper roll 11 and the bottom roll 18 of the calender. An
advantagoues multiple-nip calender appropriate in the connection
with the invention is the multiple-nip calender marketed by the
applicant under trademark Optiload.TM.. Both the upper roll and the
bottom roll are polymer rolls and in said second embodiment of the
invention, the calendering nip N is formed between a flexible
calendering belt 133, arranged to be pressed against the polymer
roll 11 and 18 with the aid of tension devices. Thus, the polymer
roll 11 and 18 serves also in the calendering arrangement of the
present embodiment as a stop roll for forming a calendering nip N.
As can be seen in the figure, for the tension devices of the
calendering belt 133, a first, second, third and fourth guide roll
132 are used in the second embodiment of the invention, around
which the endless calendering belt 133 passes. One of the guide
rolls, the first top left guide roll 132 in the nip N against the
bottom roll 18 and the guide roll 132 down on the left in the nip N
against the upper roll 11, can be positioned in vertical direction,
whereby the tension of the calendering belt 3 and pressing against
the polymer roll 11 or 18 acting a the stop roll as well as the
length of the calendering nip N can be adjusted.
[0025] As advantageous embodiments of the invention a one-nip
calender may be furthermore mentioned, whereby the calendering nip
of the invention having the capacity to produce mat quality is the
only nip of the calender, and a multiple-nip calender, whereby
advantageous targets for application is the forming of a
calendering nip of the invention producing mat quality against the
upper roll of a multiple-nip calender or against a bottom roll of a
multiple-nip calender.
[0026] The invention is described in the foregoing in exemplary
fashion, referring to the figures of the accompanying drawing.
However, the invention is not restricted to concern solely to
examples associated with supercalender presented in the figures,
instead, various embodiments of the invention may, related to
various multiple-nip calenders, be varied within the inventive idea
determined in the accompanying claims.
* * * * *